US5194874A - Satellite antenna tracking system - Google Patents
Satellite antenna tracking system Download PDFInfo
- Publication number
- US5194874A US5194874A US07/677,623 US67762391A US5194874A US 5194874 A US5194874 A US 5194874A US 67762391 A US67762391 A US 67762391A US 5194874 A US5194874 A US 5194874A
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- US
- United States
- Prior art keywords
- antenna
- signal
- scan
- error
- receiver
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 238000012937 correction Methods 0.000 abstract description 13
- 238000001514 detection method Methods 0.000 abstract description 12
- 238000000034 method Methods 0.000 description 11
- 238000004891 communication Methods 0.000 description 4
- 238000013461 design Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 208000004350 Strabismus Diseases 0.000 description 1
- 230000003044 adaptive effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000010365 information processing Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
- H01Q3/02—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical movement of antenna or antenna system as a whole
- H01Q3/08—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical movement of antenna or antenna system as a whole for varying two co-ordinates of the orientation
- H01Q3/10—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical movement of antenna or antenna system as a whole for varying two co-ordinates of the orientation to produce a conical or spiral scan
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S3/00—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received
- G01S3/02—Direction-finders for determining the direction from which infrasonic, sonic, ultrasonic, or electromagnetic waves, or particle emission, not having a directional significance, are being received using radio waves
- G01S3/14—Systems for determining direction or deviation from predetermined direction
- G01S3/58—Rotating or oscillating beam systems using continuous analysis of received signal for determining direction in the plane of rotation or oscillation or for determining deviation from a predetermined direction in such a plane
Definitions
- the present invention relates to a system for accurately pointing tracking antennas found in satellite communications.
- the system is designed for an antenna using the mechanical conical scan method of tracking.
- the antenna system uses a modulated automatic gain control signal to control error circuitry which generates signals which can drive an actuator which governs the movement of the antenna.
- the system can effectively sense directional errors in the antenna and correct these pointing errors utilizing the same circuitry and the same actuator, eliminating the need for separate error sensing and error correcting equipment in the antenna.
- a typical implementation for a mechanical conical scanning antenna system is where the antenna is of the Cassegrain type.
- a subreflector In the Cassegrain configuration a subreflector is rotated at high speed so as to obtain a mechanical conical nutation within a certain angle of rotation which defines the scan region covered by the antenna beam.
- the conical scan can determine errors in the positioning of the antenna, since the amplitude of the received signal will be modulated by the mechanical nutation imparted by the rotating subreflector.
- a separate device typically an elevation over azimuth actuator is used to finally position the antenna structure.
- the present invention relates to a tracking system for an antenna which is capable of performing a mechanical conical scan.
- Mechanical conical scanning techniques have been known in the art, and are typically used for detecting positional errors in the pointing of the antenna.
- the antenna subsystems which detect and correct these pointing errors are the same, therefore providing improved design economy and greater flexibility in the application of the antenna to a variety of uses.
- the antenna which comprises a reflector and an antenna feed, is mounted upon an actuator which is capable of moving the antenna in two directional planes around two axes.
- the antenna When the antenna is made to mechanically nutate in a conical scan pattern, if any error is present in the directional positioning or pointing of the antenna with relation to the signal, the signal being received by the antenna will modulate as a result of the nutative movement of the conical scan.
- This received signal is sent to a receiver in the antenna system.
- the receiver contains an Automatic Gain Control (AGC) circuit.
- AGC Automatic Gain Control
- This AGC circuit will generate an AGC signal which is modulated proportionately with the RF signal modulation imparted by the conical scan of the antenna.
- This modulating AGC signal is compared to a local reference sine wave signal, and an error signal is generated when AGC signal modulation is present.
- the error signal is in turn fed to the actuator which drives the antenna, which causes the actuator to drive the antenna in a direction such that the error signal is minimized or eliminated.
- the same actuator and control circuits are used when the antenna is seeking a signal, that is at the commencement of nutative movement, as well as when the antenna has found a signal and is correcting its position relative to that signal, that is when the nutative movement is brought under control and final directional positioning of the antenna takes place.
- FIG. 1 is a box diagram representation of an error tracking and correcting antenna system known in the prior art
- FIG. 2 is a box diagram representation of the antenna system of the present invention.
- FIG. 3 is a representation of one possible implementation of the present invention, namely an offset feed configuration
- FIG. 4 is another possible implementation of the present invention, namely an offset reflector configuration.
- the acquisition field within which signals to be carried may be searched out is narrower in these systems due to the RF characteristics of the sensors used, either in monopulse or sequential lobing systems.
- the system of the present invention requires a single RF sensor 3, receiver 4 and a single actuator 2 to implement signal error detection and correction.
- Signal error detection and correction in the present invention is implemented as follows.
- the antenna 1 is movably mounted on an actuator 2 which is capable of movement in two directions along two separate axes.
- the actuator 2 can move the antenna 1 in a nutative fashion, causing the antenna beam to move in a conically shaped pattern resulting in what is known in the art as a conical scan.
- Actuator 2 is fed an actuating signal D from adding circuit 7.
- Adding circuit 7 generates actuating signal D by adding an error signal B received from detector 5 and a sinusoidal signal C received from local oscillator 6.
- Local oscillator 6 provides an extremely low frequency sine wave (corresponding to the scan rate of the conical scan), in the order of less than 10 Hertz (Hz) and preferably in the order of 0.1 to 0.5 Hz. If no error signal B is present in the adding circuit 7, the only signal received by actuator 7 is the sinusoidal signal C emitted by local oscillator 6.
- the actuator signal D causes actuator 2 to impart nutative movement to the antenna 1. This nutative movement causes the antenna to scan in a conical pattern. This can be considered the error detection or seeking mode, that being when no RF signal has yet been received by the antenna 1, or the RF signal being received falls outside certain parameters.
- the received signal When an RF signal is received while the conical scan is being conducted, the received signal will have a modulation imposed upon it by the conical scan as a result of the nutational movement of the antenna.
- This modulated RF signal is fed to the receiver 4.
- Receiver 4 contains an Automatic Gain Control (AGC) circuit of a type commonly known in the art. Since the RF signal received by the antenna is modulated, the RF signal modulation envelope will be imposed upon the AGC signal. This modulated AGC signal is fed to detector 5.
- the AGC voltage will modulate at the conical scan rate at which the antenna is being nutated, with an amplitude corresponding to the signal strength of the received RF signal. It is preferable that the conical scan rate be performed at a frequency lower than 10 Hz, preferably within the range of approximately 0.1 to 0.5 Hz.
- Local oscillator 6 signal E is fed to detector 5 along with the modulated AGC signal. These signals are then compared and processed and an error signal B is generated which is fed to an adding circuit 7.
- Local oscillator 6 also feeds sinusoidal reference signal C to adding circuit 7.
- Adding circuit 7 combines the error signal B with the local oscillator reference sinusoidal signal C.
- Adding circuit 7 generates the actuating signal D which feeds actuator 2 which governs the antenna 1 movement.
- the detector 5 generates an error signal such that when the error signal B and reference sinusoidal signal C are added together it causes the actuator to modify the nutational movement in such a way as to seek to minimize the modulation on the RF signal and in turn the modulation imposed on the AGC signal of receiver 4.
- This signal error correction takes place by gradually modifying the nutational movement imposed by actuator 2 on antenna 1 and thereby gradually narrowing the conical pattern of conical scan until the antenna reaches a point where there is no modulation on the RF signal, at which point nutational movement ceases.
- the antenna will be conically scanning at its maximum rate until an RF signal is received, at which point the modulation of the RF signal causes the nutational movement to gradually modify itself until the modulation disappears and nutation ceases altogether.
- the same antenna subsystems control the nutative movement of the antenna, both during seeking and during final positioning, eliminating the need for separate, specialized components.
- the signal sensing function is performed by the same RF sensor 3 and receiver 4 that is used for RF information processing on the particular RF channel which the antenna is designed to operate at, thereby allowing optimization of the RF sensor for the frequency selected.
- the AGC signal implementation is very common, and therefore the detector 5, adding circuit 7 and oscillator 6 and actuator 2 are operated independently of the RF frequency at which sensor 3 and receiver 4 are designed to operate. Since these components are non-RF components, they are easier to maintain, simpler to design, and less expensive to operate.
- the antenna configuration of the present invention is extremely flexible since the RF characteristics can be readily changed without modifying the control system, therefore making it useful for a number of different RF applications with relatively simple modification.
- the conical scan imposed will create a conical pattern which revolves around an imaginary axis known as the scan axis.
- a typical RF antenna has a beam width which is developed around an imaginary axis known as the beam axis of the antenna. It is very common to refer to the -3db beamwidth. This -3db beamwidth is referred to as a particular angle.
- the conical scan axis and the antenna beam axis are at some given angle to each other as these axes rotate in space relative to each other.
- the angle at which the scan axis and the beam axis lie during conical scanning is referred to as the semiaperture angle or squint angle. It is preferable, due to the low scanning frequency of the system of the present invention that this angle be kept within a range of approximately between 1/20th and 1/10th of the antenna -3db beamwidth. However, during the initial nutative movement or the error detection phase of the conical scanning process, the angle may be increased to values corresponding to approximately 1/5th 1/2 of the -3db beamwidth, by adaptive techniques commonly known in the art.
- the ability to adapt the parameters of the mechanical scan of the antenna to commonly known techniques, and the ability of the system to operate in multiple RF applications provides great advantages and flexibility in the application of such an antenna system.
- the error detection and correction methodology used in the present invention can be used in RF applications regardless of signal modulation schemes. This is true so long as such modulation schemes do not have significant spectrum components within the narrow band closely related in frequency to the mechanical conical scan.
- the RF signal received may be, for instance, a frequency modulated analog or phase modulated digital signal, a multicarrier signal such as frequency division multiplex (FDM) with any modulation within each carrier (analog or digital), a single side band modulated signal (so long as the lower end of the voice band is far higher than the mechanical scan frequency), a multicarrier signal with random access and expanded spectrum modulation, etc.
- FDM frequency division multiplex
- An application which is considered considerably well suited for the use of the system of the instant invention is in intersatellite RF communication links in the centimeter and millimeter wavelength bands.
- the antennas typically have reduced dimensions (from 0.5 meters to 2 meters) and the dynamics of the relative motion among satellites are characterized by low angular speeds.
- the inventive system is also considered useful for establishing RF connections between satellites in synchronous orbit and mobile terminals on earth, operating in the centimeter and millimeter wavelength bands which are either stationary or moving.
- FIGS. 3 and 4 Two illustrative configurations of such an antenna system are shown in FIGS. 3 and 4.
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Variable-Direction Aerials And Aerial Arrays (AREA)
- Arrangements For Transmission Of Measured Signals (AREA)
Abstract
Description
Claims (9)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IT47798A/90 | 1990-03-28 | ||
IT47798A IT1240809B (en) | 1990-03-28 | 1990-03-28 | INTEGRATED SENSOR-ACTUATOR SYSTEM FOR THE CONTROL OF THE AIMING OF ANTENNAS ON BOARD ARTIFICIAL SATELLITES. |
Publications (1)
Publication Number | Publication Date |
---|---|
US5194874A true US5194874A (en) | 1993-03-16 |
Family
ID=11262573
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US07/677,623 Expired - Fee Related US5194874A (en) | 1990-03-28 | 1991-03-28 | Satellite antenna tracking system |
Country Status (3)
Country | Link |
---|---|
US (1) | US5194874A (en) |
EP (1) | EP0449155A3 (en) |
IT (1) | IT1240809B (en) |
Cited By (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5351060A (en) * | 1991-02-25 | 1994-09-27 | Bayne Gerald A | Antenna |
US5729240A (en) * | 1995-07-24 | 1998-03-17 | Alcatel Telspace | Method of controlling a non-geostationary satellite antenna positioner |
EP0918367A2 (en) * | 1997-11-19 | 1999-05-26 | RR ELEKTRONISCHE GERÄTE GmbH & Co. KG | Tracking control system and method for alignment of a pivoting reflector antenna with a radiating source |
US6307523B1 (en) | 2000-05-15 | 2001-10-23 | Harris Corporation | Antenna apparatus and associated methods |
US20030134592A1 (en) * | 2002-01-11 | 2003-07-17 | Franzen Daniel R. | Apparatus and method to implement a flexible hub-spoke satellite communications network |
US6690332B1 (en) * | 1999-04-22 | 2004-02-10 | Saabtech Electronics Ab | Antenna method and device with predictive scan position |
US20040066344A1 (en) * | 2002-10-08 | 2004-04-08 | Eric Amyotte | Steerable offset antenna with fixed feed source |
DE10332777B3 (en) * | 2003-07-17 | 2005-03-10 | Deutsch Zentr Luft & Raumfahrt | A method of aligning a vehicle-mounted directional antenna of a satellite signal receiver with a communications satellite |
US20070063911A1 (en) * | 2003-06-16 | 2007-03-22 | Davidson D | Cellular antenna and systems and methods therefor |
WO2007118211A3 (en) * | 2006-04-06 | 2008-11-27 | Andrew Corp | A cellular antenna and systems and methods therefor |
US20090061941A1 (en) * | 2006-03-17 | 2009-03-05 | Steve Clark | Telecommunications antenna monitoring system |
US20110156956A1 (en) * | 2008-12-17 | 2011-06-30 | Asc Signal Corporation | Subreflector Tracking Method, Apparatus and System for Reflector Antenna |
US9196950B1 (en) * | 2012-12-11 | 2015-11-24 | Siklu Communication ltd. | Systems and methods for vibration amelioration in a millimeter-wave communication network |
CN106299696A (en) * | 2015-05-13 | 2017-01-04 | 中国科学院空间科学与应用研究中心 | A kind of method utilizing received signal level to realize automatically controlling tracking antenna |
US10483637B2 (en) | 2015-08-10 | 2019-11-19 | Viasat, Inc. | Method and apparatus for beam-steerable antenna with single-drive mechanism |
US11115108B2 (en) * | 2019-10-25 | 2021-09-07 | Tata Consultancy Services Limited | Method and system for field agnostic source localization |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2934763A (en) * | 1949-02-28 | 1960-04-26 | Hopkins Cleveland | Rapid scanning antenna directive system |
US2954554A (en) * | 1957-02-11 | 1960-09-27 | Hazeltine Research Inc | Radar synchronizing apparatus |
US3745582A (en) * | 1970-09-28 | 1973-07-10 | Nippon Telegraph & Telephone | Dual reflector antenna capable of steering radiated beams |
-
1990
- 1990-03-28 IT IT47798A patent/IT1240809B/en active IP Right Grant
-
1991
- 1991-03-24 EP EP19910104609 patent/EP0449155A3/en not_active Withdrawn
- 1991-03-28 US US07/677,623 patent/US5194874A/en not_active Expired - Fee Related
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2934763A (en) * | 1949-02-28 | 1960-04-26 | Hopkins Cleveland | Rapid scanning antenna directive system |
US2954554A (en) * | 1957-02-11 | 1960-09-27 | Hazeltine Research Inc | Radar synchronizing apparatus |
US3745582A (en) * | 1970-09-28 | 1973-07-10 | Nippon Telegraph & Telephone | Dual reflector antenna capable of steering radiated beams |
Cited By (23)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5351060A (en) * | 1991-02-25 | 1994-09-27 | Bayne Gerald A | Antenna |
US5729240A (en) * | 1995-07-24 | 1998-03-17 | Alcatel Telspace | Method of controlling a non-geostationary satellite antenna positioner |
EP0918367A2 (en) * | 1997-11-19 | 1999-05-26 | RR ELEKTRONISCHE GERÄTE GmbH & Co. KG | Tracking control system and method for alignment of a pivoting reflector antenna with a radiating source |
EP0918367A3 (en) * | 1997-11-19 | 2004-01-21 | RR ELEKTRONISCHE GERÄTE GmbH & Co. KG | Tracking control system and method for alignment of a pivoting reflector antenna with a radiating source |
US6690332B1 (en) * | 1999-04-22 | 2004-02-10 | Saabtech Electronics Ab | Antenna method and device with predictive scan position |
US6307523B1 (en) | 2000-05-15 | 2001-10-23 | Harris Corporation | Antenna apparatus and associated methods |
US6973287B2 (en) * | 2002-01-11 | 2005-12-06 | Northrop Grumman Corporation | Apparatus and method to implement a flexible hub-spoke satellite communications network |
US20030134592A1 (en) * | 2002-01-11 | 2003-07-17 | Franzen Daniel R. | Apparatus and method to implement a flexible hub-spoke satellite communications network |
US6747604B2 (en) * | 2002-10-08 | 2004-06-08 | Ems Technologies Canada, Inc. | Steerable offset antenna with fixed feed source |
US20040066344A1 (en) * | 2002-10-08 | 2004-04-08 | Eric Amyotte | Steerable offset antenna with fixed feed source |
US8018390B2 (en) * | 2003-06-16 | 2011-09-13 | Andrew Llc | Cellular antenna and systems and methods therefor |
US20070063911A1 (en) * | 2003-06-16 | 2007-03-22 | Davidson D | Cellular antenna and systems and methods therefor |
DE10332777B3 (en) * | 2003-07-17 | 2005-03-10 | Deutsch Zentr Luft & Raumfahrt | A method of aligning a vehicle-mounted directional antenna of a satellite signal receiver with a communications satellite |
US20090061941A1 (en) * | 2006-03-17 | 2009-03-05 | Steve Clark | Telecommunications antenna monitoring system |
WO2007118211A3 (en) * | 2006-04-06 | 2008-11-27 | Andrew Corp | A cellular antenna and systems and methods therefor |
US20110156956A1 (en) * | 2008-12-17 | 2011-06-30 | Asc Signal Corporation | Subreflector Tracking Method, Apparatus and System for Reflector Antenna |
US9196950B1 (en) * | 2012-12-11 | 2015-11-24 | Siklu Communication ltd. | Systems and methods for vibration amelioration in a millimeter-wave communication network |
CN106299696A (en) * | 2015-05-13 | 2017-01-04 | 中国科学院空间科学与应用研究中心 | A kind of method utilizing received signal level to realize automatically controlling tracking antenna |
CN106299696B (en) * | 2015-05-13 | 2019-10-11 | 中国科学院国家空间科学中心 | A method of it is realized using received signal level and automatically controls tracking antenna |
US10483637B2 (en) | 2015-08-10 | 2019-11-19 | Viasat, Inc. | Method and apparatus for beam-steerable antenna with single-drive mechanism |
US10998623B2 (en) | 2015-08-10 | 2021-05-04 | Viasat, Inc. | Method and apparatus for beam-steerable antenna with single-drive mechanism |
US11476573B2 (en) | 2015-08-10 | 2022-10-18 | Viasat, Inc. | Method and apparatus for beam-steerable antenna with single-drive mechanism |
US11115108B2 (en) * | 2019-10-25 | 2021-09-07 | Tata Consultancy Services Limited | Method and system for field agnostic source localization |
Also Published As
Publication number | Publication date |
---|---|
EP0449155A2 (en) | 1991-10-02 |
IT1240809B (en) | 1993-12-17 |
IT9047798A0 (en) | 1990-03-28 |
EP0449155A3 (en) | 1992-11-25 |
IT9047798A1 (en) | 1991-09-28 |
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Legal Events
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Owner name: SELENIA SPAZIO S.P.A. Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:PERROTTA, GIORGIO;REEL/FRAME:005772/0209 Effective date: 19910606 |
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